Monday 11 October 2010 11.49 EDT
First published on Monday 11 October 2010 11.49 EDT

William Hague today defended the decision to try to rescue Linda Norgrove, after David Cameron revealed it is now thought the British aid worker was killed by US troops rather than her captors.

In a statement to MPs in the Commons this afternoon, the foreign secretary paid tribute to the US forces in Afghanistan who had "risked their lives to rescue a British subject" after her kidnap, and cautioned against a rush to judgment.

The shadow foreign secretary, Yvette Cooper, said "we condemn utterly the actions of the hostage-takers throughout these events", but added: "There are important questions that now do arise" about the nature of the authorisation Hague gave to the operation and his level of involvement.

The prime minister announced this morning that a full UK-US investigation was being launched into the circumstances surrounding Norgrove's death on Friday. Hague told MPs "we are still designing the form of the investigation" and deciding whether it would take place under the auspices of Isaf (Nato forces in Afghanistan) or the US military with UK involvement.

The foreign secretary said security officials had concurred that the longer Norgrove was held the greater the risk to her life. He said that within hours of her kidnap he authorised a rescue operation to be mounted "at the earliest opportunity". His decision was based on the assessment that she was "in grave danger" and could be transferred to more inhospitable territory.

He said she was being held by Salafists with links to the Talban and al-Qaida and a rescue operation was the only realistic prospect for her release.

"From the very start Cobra [the government's emergency response committee] assessed that Linda's life was in grave danger which is why I authorised, from the very beginning, a rescue attempt to be made in the right circumstances," said Hague.

He added: "We had information from the outset that the objective of Linda's captors was to pass her further up the Taliban command chain and perhaps move her to even more inaccessible terrain. On the basis of the information available to us we were in no doubt whatsoever that there was a continual and real threat to her life and no credible option for a negotiated release."

The foreign secretary said he regretted the release of information over the weekend that suggested Norgrove had been killed by her captors but said it was a consequence of the government erring on the side of transparency.

Cameron revealed earlier today that General David Petraeus, the commander of Nato forces in Afghanistan, had contacted his office this morning to say a review of the rescue operation had revealed Norgrove "may not have died at the hands of her captors" as originally thought.

It had initially been reported that Norgrove died from a grenade explosion, but subsequently Nato claimed she had been killed when an insurgent detonated a bomb strapped to his body as American troops attempted to rescue her.

Cameron said: "Linda's life was in grave danger from the moment she was taken ... He [Petraeus] and US forces did everything in their power to bring Linda home safely."

He added: "In the end this is an issue of a very difficult judgment ... You can never be certain that an option like this will lead to the rescue of the hostage ... In the end you have to make a decision whether to go ahead or not." He said he felt like it had been the right decision based on what the UK and US knew at the time.

"You will understand that I cannot discuss the intelligence information that led us to decide that a rescue operation was the best choice," Cameron said.

Norgrove, 36, was killed in the raid by US forces in Afghanistan's eastern Kunar province, after she and three colleagues were kidnapped two weeks earlier.

The Guardian understands that Cameron and William Hague, the foreign secretary, were advised by MI6 and SAS officers before agreeing to the plan to rescue Norgrove. Her family was unlikely to have been informed.

It was agreed that US, rather than British, special forces, should be involved because the Americans knew the area better.

Asked if he had considered using British special forces to rescue Norgrove, the prime minister said: "Of course I asked a huge number of questions." He said he followed the advice of Petraeus, who was on the ground, adding that it would have been strange to overrule the advice of US officials.

Cameron said he was "deeply sorry" that the situation had "not worked out the way we all wanted it to".

He also thanked US forces for their "courage", and said statements made on Saturday as to how Norgrove died, which now appear to be incorrect, were made in good faith.

Asked whether there was any suggestion US forces were reckless, the prime minister said: "We must get to the bottom of what happened; we only have sketchy information." Petraeus "deeply regrets what happened, as do I", Cameron said.

Originally from Sutherland in the Scottish Highlands, Norgrove was seized by militants in Kunar province on 26 September.

Three Afghan nationals also taken by the insurgents were later released, but Norgrove continued to be held amid growing concern.

A former United Nations employee, she was working for the firm Development Alternatives Inc at the time of her kidnap. Based in Jalalabad, she supervised reconstruction programmes in the eastern region of Afghanistan funded by the US government.

Cameron said: "Linda's death is a tragedy for her family and those who worked alongside her in Afghanistan. She was a dedicated professional doing a job she loved in a country she loved."

Cameron informed Norgrove's family of the "deeply distressing development" before making his announcement at a scheduled press conference that was delayed by almost an hour this morning.

Speaking from the Isle of Lewis today, Norgrove's father, John Norgrove, said: "We are not saying anything to the press at the moment. We might issue a statement in another day or two, we're not certain, but now we are not saying anything." Asked whether that was the case in the light of Cameron's comments today, Norgrove said: "We are just saying that, end of story."

Western Isles SNP MSP Alasdair Allan said the family deserved the "fullest facts" about what had happened to their daughter. "They deserve the truth," he said. "I know Afghanistan is a difficult place to operate in but everybody deserves the truth over what happened – especially the family. I will be meeting with them today to given them my support."

Cameron said the decision to mount a rescue operation was made by Hague "after careful consideration" and had his full support as prime minister.

"I am clear that the best chance of saving Linda's life was to go ahead, recognising that any operation was fraught with risk for all those involved and success was by no means guaranteed," said Cameron.

"None of us can understand just how painful this must be for Linda's family," he said.

"I want to assure Mr and Mrs Norgrove that I will do everything I possibly can to establish the full facts and give them certainty about how their daughter died."

Cameron said Petraeus had treated the hostage "as if she was a US citizen" and that "he and the US forces did everything in their power to bring Linda home safely".

"The US forces placed their own lives in danger. General Petraeus has told me they are deeply dismayed at the outcome. I want to thank them for their courage," he said, adding: "We have to now have this investigation to find out what happened and if bad mistakes were made."

Last year a British commando raid on a Taliban hideout rescued kidnapped New York Times reporter Stephen Farrell, who has British and Irish citizenship. But Farrell's Afghan translator Sultan Munadi and a woman and child were killed in the raid, raising questions about whether military force should have been used.

The investigation

US Central Command has named a special operations officer, Major General Joseph Votel, to head the investigation. In a statement, Central Command said the investigation team would work "in close co-operation with UK authorities".

The fact the investigation will be led by Central Command may concern those who have called for independent inquiries in the past.

Lieutenant Colonel Mike Lawhorn, a spokesman for US Central Command, said there was no set deadline for the inquiry but it would be done as speedily and thoroughly as possible.

Votel, who will have one or more British representatives in the team, will look over the surveillance, listen to audio recordings of the raid and interview members of the special forces team involved.

Lawhorn said a member of the team had said initially that he thought one of the captors had set off an explosive device, but had not said it was a suicide vest, as reported by a British government official.

Lawhorn said they did not know if it was a hand grenade or not.

"We are not doing this because it was a hand grenade. We are doing it because of conflicting bits of evidence. We do not know what is was," he said.

When the investigation is complete, it will be shown first to the British government and the Norgrove family because being released.

Lieutenant Colonel John Dorrian, a spokesman at Nato headquarters in Kabul, said today the investigation came about after the rescue mission leader saw video footage of the raid, talked with members of the rescue team, and decided "it was not conclusive what the cause of her death was". The rescue mission leader spoke with Petraeus, who requested the investigation, Dorrian said.